1. Field of the Invention
This invention relates in general to the construction of containers and, in particular, to a new and useful container having a shell or body portion of cylindrical shape with a semi-cylindrical end portion closing each end, each having a longitudinal axis which extends substantially perpendicular to the longitudinal axis of the shell.
2. Description of the Prior Art
Containers, particularly those made of synthetic materials or steel are known of various types of construction. Above all, there are known ones which comprise a cylindrical shell having outwardly vaulted bottoms or ends and socket pieces which are welded thereon. In respect to the vaulted bottoms, they may be generally flat vaulted and high vaulted types. Flat vaulted bottoms frequently are dis-satisfactory from the standpoint of their mechanical properties insofar as they show a diaphragm effect. Such a diaphragm effect is disadvantageous particularly when they are subject to an alternate or swelling internal pressure. In order to reduce the diaphragm effect by improved mechanical properties of container bottoms, it is possible to provide bottom walls of substantially greater thickness in comparison to the container shell walls. In such cases, however, unfavorable stress conditions occur in the transition zones between the container shell and the ends or bottoms. This may lead to temporary overstressing or permanent rupture due to the variable load resulting from the alternating or swelling internal pressures. For this reason, the use of semispherical container bottoms has come into use. Such container bottoms do not show practically any diaphragm effect, and their mechanical properties are optimal. A principal disadvantage, however, is the cost of manufacture. It is very difficult to manufacture semispherical bottoms. Larger bottoms of this type must be welded together of several pieces. So far, unfavorable stress conditions cannot entirely be avoided in semispherical container bottoms and difficulties arise particularly from the necessity to attain dimensional accuracy in the welding of the bottoms to the container shell.